May 7, 2014

Dinosaur Claws Were Used For More Than Just Ripping Flesh: Study

The claws of Tyrannosaurus rex and Velociraptor are probably best known for ripping through the flesh of hapless prey, but a new study published in Proceedings of the Royal Society B has found that this family of dinosaurs, known as theropods, probably used its claws for a variety of purposes.

In the study, Stephan Lautenschlager, from Bristol University, examined the differences in claw shape among theropods and analyzed them based on how the various shapes are related to different functions.

"Theropod dinosaurs were all bipedal, which means their forelimbs were no longer involved in walking as in other dinosaurs,” Lautenschlager said. “This allowed them to develop a whole new suite of claw shapes adapted to different functions."

The UK scientist focused on the therizinosaurs, a unique subfamily of theropods that roamed the Earth between 145 and 66 million years ago. Therizinosaurs were huge animals, as much as 23 feet high, with claws over 19 inches long, elongated necks and had a coating of down-like feathers. Therizinosaurs were also unique theropods in that they were tranquil herbivores.

To recognize how distinct claws on the forelimbs of these dinosaurs were used, Lautenschlager scanned the claws of 65 species and generated comprehensive computer models based on these scans to replicate various potential functions for distinct species and claw shapes. The claws were also contrasted to the claws of modern-day mammals, with known functions.

Throughout their evolution, several theropod subfamilies, including therizinosaurs, transformed from being carnivores to subsisting on a diet of plants. The new research showed that, throughout this transition, theropod dinosaurs evolved a wide variety of claw morphologies tailored to particular functions, such as excavating, grasping or striking.

"It's fascinating to see that, with the shift from a carnivorous to a plant-based diet, we find a large variety of claw shapes adapted to different functions,” Lautenschlager said. “This suggests that dietary adaptations were an important driver during the evolution of theropod dinosaurs and their transition to modern birds."